Fuse



Jan. 24, 1950 p H, THOMPSON 2,495,432

FUSE

Original Filed May 27, 194 4 iPatented Jan. Z4, 195'() NITED STATES gere-2 .i orrlee FUSE Parke H. Thompson, Kirkwood, Mo., assigner to Amp Corporation, St. Louis, Mo., a corporation of Missouri 7 Claims.

rihis invention relates to fuzes, and with regard to certain more specific features, to point-detonating fuzes for projectiles and the like.

This application is a division of my copending application -Serial No. 537,563, filed May 27, 1944, for Fuze.

Among the several objects of the invention may be noted the provision of a completely safe, simple, compact and permanently reliable pointdetonating fuze for projectiles and the like; the provision of a fuze of the class described, which has delayed arming after it leaves a gun barrel after which it remains armed until it strikes the desired target, and which will not be fired by preliminary passage through unimportant objects such as rain drops, leaves, camouflage and the like; and the provision of a fuze of this class which is easy to manufacture. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is illustrated one of various possible embodiments of the invention,

Fig. 1 is a longitudinal section ofthe new fuze, 2

showing it in the unarmed or safe condition of its parts;

Fig. 2 is a fragmentary view similar to Fig. 1 showing the parts in armed condition;

Fig. 3 is a vertical sectiontaken on line 3 3 of Fig. l;

Fig. 4 is a vertical section taken on line 4 4 of Fig. l; and,

Fig. 5 is a fragmentary detail of certain parts of Fig. i prior to complete assembly.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

The invention is an improvement upon the construction shown in Scelzo United States Patent 2,155,100, dated April 18, 1939. It is applicable to various classes of ammunition, for both small and large calibers. However, it has particular advantages in connection with the smaller and medium sizes because of the small space within which the elements of the invention may be housed.

, Referring now more particularly to Fig. 1, there is shown at numeral l a tapered fuze body having a hollow threaded shank 3 for application to the threaded endof a shell 5 shown in dot- 2 1 l dash lines. The shell as usual carries the main explosive charge to be detonated by the fuze per se. The shank 9 is formed interiorly as a hollow cylinder I for receiving a cylindric pre-consolidated pellet of booster charge material I3. This material is held in place by means of a .so-called Welsh plug 9 pressed into an undercut peripheral recess II.

Since the manner of applyingthe plug 9 is of some importance, the details of this will be explained, referring to Fig. 5. .This plug is initially bulged as shown in Fig. 5,-with a cylindric mar'- gin which will allow it to zbe snugly inserted into the nari-cwest portion of an undercut groove Ii. This is done after the pre-consolidated booster charge pellet I3 has been slipped into the cylinder "i, This pellet is about equal to or if necessary slightly longer than the cylinder l measured out to the base of the groove I I. Thereafter, the plug 9 is pressed from the bulged condition shown in Fig. 5 to the fiat condition shown in Fig. 1. This expands its margin to interlock inthe undercut groove I I. At the same time its central portion exerts a nal re-consolidating veffect upon the booster charge i3, thus assuring that the latter will entirely compactly ll up the space in the cylinder l. the pellet i3 of the detonating wave which is to set it olf. Unreliable booster charge action is often due to its improper consolidation in its containing chamber, and this method of re-consolidating it by means of the holding plug 9 increases its reliability.

Extending forward from the cylinder I on the center line of the body I is a cylindric connecting passage I9. At the -rear end of this passage is a crimping groove I7 for receiving a flange I9 of a primer cup 2l, closed at its opposite end as shown at 23. This is sometimes known as a leading cup, being filled with an explosive such as tetryl.

Beyond the'passage I5, the body l is provided with 'a counterbore 25. This counterbore 25 connects with the passage I5 by means of a spherical seat 2l. The largest'diameter -of the seat 2i ris preferably smaller than the diameter of the ccunterbore 25 for reasons which will appear.

Extending at an angle from one side of the counterbore 25 is a passage 29 for accommodating an angularly located cantilever" wire spring 3! which is'staked into the bottom of the passage as indicated at 33. I Obviously, other methods for fastening the spring may be employed. The cross section of the passage Z9 is optional but a round bore is shown. -The counterbore 25 also includes atits outer end a keyway`35rfor a key 3l. Key 31 This assures reliable travel through 3 also seats in a keyway 4I in a nose 39. equivalent key means may be used.

Adjacent to, and connecting with the hole 29 in body I, the nose 39 is provided with a radial recess 43 accommodating movement of the end of spring 3d, as be seen by comparing Figs. 1 and 2. The nose 35 has a central passage orbore 45 communicating with the recess 43. The end 65 of spring 3l normally extends into this passage 45.

At the forward end of the opening 45 is a counterbore 47. At its rearward; end the open.- ing is iared out by means of a beveled portion 49. This beveled portion 49 is carried in an extending portion I of the nose,v determined by a seat 52. Portion 5I telescopes into the counterbore 25 of the body I. No threads are used at this point. A press fit may be used. The diameter of Other the counterbore 25 and the position of thechamfer 49 are such as just to accommodate a spherical rotor 53 which engages' the: spherical seat 27.. This. rotor is rotary the. space provided for it.

The. rotor is= bored out along an axis of symmetry A-S which passes through its geometric center. This horeconsists in a small-diameter portion 55 and a; larger col-interbore 57. Atl the large: end ofthe; connterbore 57 is a cross slot 59 which is symmetrical with respect to said axis A-S. This slot isi designed to. accommodate the spring 31@ and allow itliree; movement. The counterbore 5.7 from` theA end ofthe. bore 5,5 to the slot 55k is iilledx withV asensitive detonating charge 7l.

The normal position of spring 3l; is such as suggested inlr'lig. 1..v that is theA rotor- 53 is maintained with thev axis: of symmetry A-S at an angle; with respect to; the center' line of the fuze, which greater than 45.. preferably of the order of: 7105 orso'. The. exact value of this angle isA not critical]| but; it is important thatr it bel over 45 or so, in order that in its safe condition the euiiet 5 5 0i the eeunterbete 5J- may be presented bef the eeuriterberei 2 .-.entheeutsde of the Spherieai Seat.. 21:, The puis YSe 0ithiswill appear. The bias 0f the. Serine is' inward toward the centerJ line. of the Eme; son thatl it tends to, seat the refer 01,1. Seat- 21 er; et least prevents it, from movi-ile. @heut in the, Seaee.- provided for it.

the bore 45 et the nose 39g is a hollow firing am. 6:1; which. @as be @een et the front as. indieeied: ai; S3 and; eleeedf et, the rear as indicated et 6.4.- 'Ehe peint 6:1: 0i this ein extends from the eileleeure 54.-. On they periphery of the enclosure S4 and around the point 67 is anV inwardly tapered- Skifi 6.9i. whiele when the firing, ein is back (Fial telf-e5; ur a, position. eut-Side. ef, the spring end 65a This.. undercertainy conditions to be described; forms an interlock for resisting radial movement ot the: spring, When the firing pin; fdrvgard,l tllS interloqkiI- lg action does not occur (Fig.` 2);. f

The outer; surtaces of.A theA body I4 and the nose 39 are machned on, a taper which may be constant as sh Wnoiiotherwise (llosely tting over the taper isA a tapered; cover, or shieldf 7i having a;truncated, closed topi. 7:3; forming a drum over the open endfi oithe @Quilteerbore 47. The area of the inside otthe dum 73:l is several times larger than the projected area. of` the'firing pin 6I; considered as a pistonT inbore 45,.

At its base, the cover- 7| is spun over as indicated at 75; inv Fig.` 5:V ThisY done after its application to the. assembled; nose 39v and body; ii. It is. not spun completely flatV against the underc ut. bottom 78 of thebody; Ig but is left slightly angular as shown. in Fig. 5. Hence when. the

fuze assembly is screwed to the shell 5, the flange 75 is springingly deformed so as to assure a perfect seal against entry into the mechanism of foreign elements. This seal prevents breathing of the atmosphere into and out of the mechanism with temperature. changes. Thus fuzes made according to the invention may be stored for much longer periods of time without deterioration of their contents.

An additional function of the cover 7I is to provide means for properly drawing the cover against the nose 38 to the body I without employment of. threads of any kind. The initial position of the spun flange 75 is angular as indicated in Fig. 5. Thus when the threaded attachment is made between the body I and the shell 5, the resulting deformation of the flange 75 has a fulcrum eect which drawsbaclr the conical cover as a= whole, thus firmly drawing it down on the nose 3S and the body I. only threads employed inthe whole construction are those for attaching the fuze as a whole to the shell 5:, those which would ordinarily be used between the nose and. the body having been eliminated.

Operation is as follows:

Regardless of the position of the firing pin Et, the normal bias. of the spring 3l is to the inward position shown in Fig. l. ltv therefore cooperates with the groove or notch 59 and holds the rotor 53: in the stated approximate '70 position of the axis; .Af-S'.` Forces due to normal handling of: the: anlmlnition are normally not ca,- pable; of deecting the spring 3 I: enough to, permit the rotor 53j to move more than a small amountV from thisI position. Furthermore, any temporary displacement of the spring 3;I under almost inconceivable conditions: of handling would be followed by prom-pt return` to the. holding position shown in Fig. l, Without imposition on the rotorv of any. forces which might send it to the annedI position. p

|lhe normal. bias ofthe spring 3=Iv tends to maintain; the rotor 53= ontheV spherical seat 27, thus sealing oli; the passage I5, from the detonating charge 77;.v E'u rl'lhermpre',t the angle or the axis A-S is such; that the: open-ing 55 from the' detonating charge is directed into-the counterbore 25 and not against the seat 27. Hence if an oversensitive detonating charge should accidentally explode of; its: ownl accord, its expansive force would not be directed against the lead: cup 2l. This preserves the booster charge I3 against detonation. 'I he expansive: force then safely expended;v in. the passages- 254 and 45. This important safety feature is due to the high angle of the axis A-S; which'. keepsv thef passage 55 forward with respect to the seat 27. This high angle has another advantage-Whichwill be explained at the proper pointhe'rei-n'..

In, View; of the; above. it. is clear that the fuze is. statically safe.

Next, assume that the shell is loaded into a iii-fled; gun: barrelh andi r'ed. by the propelfent charge (not shown). Both'v linear and' angular acceleration= then set in as the shell passes through the barrel.. This4 at-rst involves initial linearset-back forces on all: movable members.

Thus. a set-back force is operative upon the rotor 53 which. tends to'l seat it firmly upon the spherical' seat' 27. The4 chargeI is positioned symmetrically with= respect to the center line (EV-L; also thei bore 55' and groove 59 represent losses.- ofv metal from the rotor having about equal mcmente with respect to this: cen-ter linei C--L It will be noted that the so that, in view of the friction on said seat 21, the rotor maintains its safe position under linear acceleration along line C-L (Fig. l).

It will also be noted that a set-back force is operative upon the spring 3| and since it is anchored at 33 farther from the center line C-L than its free end 65, a counterclockwise moment is applied to the spring. This adds to the normal bias of the spring in helping to maintain the rotor 53 seated on the spherical seat 21. The set-back force on firing pin 6| adds to this Acoun-- terclockwise moment on spring 3| by pressing backward on the spring end 65. Thus the fuze is -bore safe, for, should the detonator 11 for some unknown reason at this time explode, the pressure at seat 21 would positively b-lock transmission of the detonation to the booster charge I3.

The linear acceleration which causes a setback force on the firing pin 6| also holds it back so that the flange 59 locks around the end of the spring 3|. Therefore as angular acceleration occurs, due to the riiiing of the gun, the flange 65 acts as an interlock preventing the centrifugal action of spring 3| from substantially moving it outward. Therefore, as long as linear acceleration continues, which is as long as the shell is in the gun barrel, the ro-tor positively remains in its safe position, as indicated in Fig. l.

The relationship between parts continues in the Fig. l position until the shell leaves the gun barrel. At this time linear acceleration ceases and linear deceleration sets in, due to frictional forces exerted upon the projectile in passing through the air. Since these forces are not applied to the floating ring pin 6|, it drifts or creeps forward toward drum 13. It should be noticed, however, that the frictional forces on the shell exert a much smaller component toward effecting angular deceleration than theyY doftoward electing linear deceleration. Therefore, although there is enough linear deceleration to cause the pin 5I to drift or creep forward, as indicated in Fig. 2, the angular velocity continues high enough so that the centrifugal force bends the spring 3| out radially from the slot 59. Since the density of the detonating charge 11 in the passage 51 is less than the density of the rotor 53, which is made, for example of commercial brass, and since A--S is an axis of symmetry between two centroids not in the same plane normal to C-L, this axis A--S- will tend to swing into coincidence with the center line C--L of the fuze assembly. In this position the centroids are co-planar. This places the passage 55 in communication with passage I5 as indicated in Fig. 2, the rotor remaining stable under rotation in the Fig. 2 position. The projectile is then armed in flight. It appears from tests that the arming in night is desirably delayed until an initial short part of the trajectory has been traversed. There are several possible explanations for this, one being that as the spring 3| releases the rotor, the latter becomes in effect a gyroscopic element free to precess the axis A-S toward axis C--L. The time required by gyroscopic precession involves the desired delay, particularly in view of the high initial angle between A-S and C-L. Toward the end of the precession, there occurs possibly also a conical nutation of A-S with respect to C-L which makes the opening v55 nutate in a circle around the opening l5 without having these openings connect until the very last stages of the movement ofthe axis A-S. 'This nutation is possible because the spring `3I at this time is disconnected.

It is of course also possible that the last part shown in Fig. 2, should the angular velocity drop to a point allowing the spring 3| to press against the armed rotor 53, the device would remain armed since the spring would simply hold the rotor in the armed position. Thus once armed, the fuze is permanently armed while in night.

Rain drops encountered by the drum 13 will not deform it and Without deformation the drum 'i3is incapable of driving the firing pin 6| backward.' Therefore premature detonation will not occur during flight in bad weather.

When the shell reaches its objective, collision with the fuze deforms the drum 13 which causes a pressure wave from drum 13 to impinge against the firing pin 6|. The projected area of the piston-like ring pin 6|, being substantially lessv than the area of the inside of the drum 13 (for example in the ratio of 1:4), any pneumatic compression drives the ring pin at a velocity higher than the deflection rate of the drum. Thus the action of the firing pin in moving backward upon impact is very fast, driving its point 61 into the detonating charge 11 which res against the lead cup 2| setting off the primer charge therein. This sets oi the booster charge |3. It is to be understood that the cup 2| may be dispensed with and the detonating charge permitted to i'ire directly down the chan nel I5 into the booster charge.

Certain advantages of the angle greater than 45 specified for the axis of symmetry A-S have alreadybeen stated. An additional one is that the effective centrifugal moment, at a given angular velocity of the shell, tending to turn the rotor from the Fig. 1 to the Fig. 2 position is maximum at 45 of A-S. Hence it is less at angles greater than 45 while the spring is latched in the rotor notch. This reduces the cam action of the bottom of the notch 59 on spring 3| under accelerating conditions in the gun barrel, since the position of rotor axis A-S during acceleration is greater than 45. This increases bore safety. p Another important feature of the invention is that the forms of the parts I, 39 and 6I lend themselves to easy manufacture by die casting. No threads are involved, except those at 3 necessary to attach the entire fuze to the shell. The integral protective cover 1I may easily be pressed or. spun. Assembly is simple and fool-proof.

Unlikev the Scelzo construction above mentioned,L the present fuze does not depend merely upon friction between the rotor 53 and its seat 21 for delaying or ypreventing arming in the gun barrel. It has a positive interlock in the spring 3| and notch 59 held by the pin 6I which positively prevents arming in the barrel. In this respect spring 3| and notch 59 may be designated as a latch. In addition, this latch interlock acts as a positive driving connection between the body I and the rotor 53 so that the latter is positively angularly accelerated at the same rate as the angular acceleration of the body. A mere frictional drive in this respect is avoided. Thus by the time that the projectile decelerates axially, the 'rotor is' positively rotating at a maximum speed. equal to that of the body I. This rassures 7 its proper arming action when the latch (3l, .59) is released by drift of the pin or striker 6 I.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from. the scope of the invention, it isintended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A fuze for projectiles comprising means constructed around a center line providing an axial opening having a rearwardperipheral seat, ak sphere in said opening having a diametral passage extending therethrough and a notch at the end of said passage, said passage and notch being symmetrically related with respect to' an axis of the sphere, said axis 4in `an unarmed condition of the fuze being positioned at an angle with respect to said center line, said Sphere being rotary on said seat in response Yto rotation of the iuze on said center line whereby said axis of symmetry will tend to become coincident with said center line, a movable cantilever spring anchored in said fuze and having a normal position in which its movable portion extends through said notch and holds the sphere in an unarmed position, said spring beingcentrifugally movable out of the notch upon rotation of the fuze around said center line, a firing pin axially movable in the part of the recess on the side of said sphere opposite to the seat, and latch means operative between the rear end of said firing pin and the forward end of said spring and adapted to hold the spring in the notch.

2. A fuze for projectiles comprising means constructed aroundv a center line providing an axial opening having a rearward spherical seat, a sphere in said opening having a diametral passage extending therethrough and a notch at the end of said passage, said passageY and notch being symmetrically related with respect to an axis of the sphere, said axis in the unarmed condition of the fuze being positioned at an angle with respect to said center line which is greater than 45, said sphere being rotary on said'. seat in response to rotation of the fuze on said center line whereby said axis of symmetry' will tend to become coincident with said center line, a movable cantilever spring anchored in said fuze. and having a normal position in which its movable portion extends through the notch to'hold the sphere in unarmedV position, said' spring being. centrifugally movable outV of the notch upon rotationi of the fuze around said center line, a ring pin axially movable in the part of the recessl which isl forward of saidY sphere, andlatch means operative between the rear end of said firing pin and the lorward end of Saidspring; upon forward linear acceleration of the projectile along said centerline. .Y

3. A i'uze for projectiles comprising' a hollow body, a seatin said .body dividing itsy hollow portion into rearward and. forward compartments, a sphere engaging said seat, said` sphere having a bore therethrough on an, axis ofY symmetry and a notch communicating with said bore and symmetrical with respect to said axis, a cantilever spring anchored in the body and extending through said notch into the forward compartment and statically holding said spherical meme ber in a positionwherein its bore is in communication only with said forwardcompartment,

a firing pin axially slidable in said forward compartment, said spring under dynamic rotation of the body being movable from said notch to permit rotation of the spherical member under the same body rotation, and a latch between saidv firing pinzand the free end of said cantilever spring preventing outward motion of the spring in a rearward position of the firing pin such as assumedV under axial acceleration of the body but permitting said motion under a forward position of the firing pin such as is assumed under axial deceleration oi' thebody.

4.A A fuze for projectiles comprising a hollow body having a longitudinal axis in which a peripheral spherical seat is arranged separating the body into a rearward compartment and a forward compartment, a spherical` rotor seating upon said seat, said rotor having a central passage symmetric-al about an'axis of the rotor and including a lateral notch, a cantilever spring wire anchored in one side of the body and having its free end in said forward compartment and intermediately passing through said notch, the angle of said spring with respect to said center line being such as normally statically to hold the rotor to said seat and to maintain a communication between said central passage of the rotor and said forward compartment, a firing pin axially movable in the forward compartment, a latch between the firing pin and the free end of said spring to prevent' the spring wire from dellecting from the notch under dynamic rotation of the projectile, rearward motion of the firing pin occurring upon linear acceleration of the projectile and applying a setback. force to the spring to increase its seating force on the rotor, said ring pin being movable forward upon deceleration of the projectile to release saidv latch and permit the spring under dyf namic rotation of the projectile to move out radially from said notch to permit the spherical member to take up its symmetrical position along said center line.

5; A fuze for projectiles comprising a truncated conical body portion having a central bore and' counterbore separated by means of a spheri" cal seat, an` angular space-forming bore communicating with said counterbore, a cantilever spring wire anchored at the bottom of said angular bore andV extending angularly inward with its movable end inthe counterbore, a spherical rotor irr said counterbore` and' engaging said spherical seat, said rotor having a symmetrical opening therethrough along an axis of the rotor and including a notch for accommodating said spring, the nose also havinga bore and a counterbor'e therein, an'extension of the nose having a telescoping t with the counterbore in the body, said bore of the nose having a lateral space communieatingV therewith and with said angular bore in the` body and accommodating motion of the movable end of the spring, a ring pin slldable in the bore of the nose, a latch at the rear of the ring pin and cooperating with the end of said spring upon setback of the firing pin under conditions ofV axial acceleration oi the'fuze and releasabl'e under conditionsv of deceleration and pin lcreep, the creep movement of the firing pin being` toward the counterbore in the nose, and a cover for the counterbore in the nose and covering said firing pin and adapted to transmit motion thereto upon impact of the projectile.

Ei.v A fuze for a projectile including a fuze body having a-bore and a seat thereima sphere in said bore engageable with the seatand having a diametral passage extending therethrough, the sphere and the seat constituting a universal mounting, said sphere being located with its center disposed substantially on the longitudinal axis of the projectile, whereby when the projectile is fired the centrifugal force of rotation of the projectile may cause the sphere to take a position wherein the diametral passage is aligned with the longitudinal axis of the projectile, a notch in the sphere, a cantilever spring anchored at one end to the body, said body having another bore on said longitudinal axis, said spring passing through said notch and having its unanchored end in said last-named bore, a firing pin movable rearwardly in the bore in response to axial acceleration of the body, latch means between the ring pin and said movable end of the spring for holding the latter in the notch until linear acceleration ceases, linear deceleration of the body causing said pin to drift into a position wherein said latch is released to allow centrifugal force to deect the spring out of said notch.

'7. A fuze for a projectile including a fuze body having a bore and a spherical seat therein, a sphere in said bore engageable with the seat and having a diametral passage extending therethrough, the sphere of the seat constituting a universal mounting, said sphere being located with its center disposed substantially on the longitudinal axis of the projectile, whereby when the projectile is fired the centrifugal force of rotation of the projectile may cause the sphere to take a 10 position wherein the diametral passage is aligned with the longitudinal aXis of the projectile, a notch in the sphere, a cantilever spring anchored at one end to the body, said body having another bore on said longitudinal axis, said spring passing through said notch and having its unanchored end in said last-named bore, a ring pin movable rearwardly in the bore in response to axial acceleration of the body, and latch means between the ring pin and said movable end of the spring for holding the latter in the notch until linear acceleration ceases, linear deceleration of the body causing said pin to drift into a position wherein said latch is released to allow centrifugal force to deflect the spring out of said notch, the free end of the spring being pointed in the direction of acceleration and being closer to the said longitudinal axis than its point of anchorage.

PARKE H. THOMPSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,155,100 Scelzo Apr. 18, 1939 FOREIGN PATENTS Number Country Date 257,335 Great Britain Aug. 2'7, 1926 837,467 France Nov. 12, 1938 

